We examined whether infants' preference for speech at 12 months is associated with autistic-like behaviors at 18 months in infants who are at increased risk for autism spectrum disorder (ASD) because they have an older sibling diagnosed with ASD and in low-risk infants. Only low-risk infants listened significantly longer to speech than to nonspeech at 12 months. In both groups, relative preference for speech correlated positively with general cognitive ability at 12 months. However, in high-risk infants only, preference for speech was associated with autistic-like behavior at 18 months, while in low-risk infants, preference for speech correlated with language abilities. This suggests that in children at risk for ASD an atypical species-specific bias for speech may underlie atypical social development.